RGB lasers have a wide variety of uses. For example, RGB lasers can be used for optical data storage, color printing, color displays, bar code scanning, multispectral detection, and reprographics.
Optical data storage is among the most common of laser applications. Optical data storage technologies include computer, compact disk ("CD") video playback, and other digital storage. Optical data storage is expected to become increasingly ubiquitous in the coming years, due in part to advances in full color and motion video, and CD photograph storage.
The success of the monochrome 300 dot per inch ("dpi") laser printers has created a need to develop color laser printing. Color laser printing applications include color facsimiles, photocopying, and laser color printing, which require 1-5 milliWatts ("mW") of power in small to medium sized laser packages.
Color display applications include personal and projection TVs, and computer graphics. The power requirements for these applications depend on the screen size, and range from 3 mW to 3 W. Advancement of this market is stalled because of size, cost, and the nature of the ion and diode lasers required to generate visible wavelength light. The main impediment to the use of RGB lasers for color displays is the development of a blue beam source.
The RGB laser may be used for colored bar code scanning. Advances in RGB lasers could result in an increased interest in colored bar code scanning.
Certain military, scientific and medical applications identify targets by observing spectral reflections of an object's surface. RGB lasers provide pure spectral sources for such detection. By using an RGB laser with a gated imaging camera having different spectral filters, numerous objects can be accurately identified at large distances. Medical applications include fiber optic probes, laboratory chemical assays, photoactivated therapies, tissue imaging, and in vivo chemical assays.
Reprographics applications include color separation, plate making and scanning. As color display systems become increasingly common, the need for color scanning systems will increase as well.
RGB lasers are generally known. U.S. Pat. No. 4,866,702 to Holly discloses a multicolored laser source comprising two Nd:YAG lasers. In Holly, a 532 nanometer ("nm") beam is generated as the second harmonic of the first laser output. The second laser output is used to generate second and third harmonics at 680 mn and 440 mn respectively.
U.S. Pat. No. 4,338,578 to Sukhman discloses a low pulse frequency RGB laser, wherein ruby laser output and Nd:YAG output are used to create three colors. The ruby laser provides a 694 mn beam which is applied to a mixing crystal; the Nd:YAG laser creates a 1064 nm beam which is also directed to the mixing crystal.
U.S. Pat. No. 5,048,911 to Sang et al. discloses a method and apparatus for coupling several laser beams of the same wavelength a single optical fiber. Sang et al. teach combining several laser beams onto a single optical fiber by separately steering each beam onto a converging lens, which lens converges the beam onto the optical fiber. The entire disclosure of each of the aforementioned U.S. patents is expressly incorporated herein by reference.
The growing number of color laser applications demands the development of smaller, more efficient RGB laser systems.